Carbonation of epoxidized soybean oil in supercritical CO2 assisted by imidazole-based organocatalysts

Production of cyclic carbonates from epoxidized vegetable oils allows to introduce CO2 into the molecular structure of renewable and highly functional resources, obtaining high added value products, which also could serve as precursors for chemicals with a high potential, such as non-isocyanate polyurethanes (NIPUs). The selection of supercritical CO2 avoids the use of organic solvents and enhances reaction yields since it helps to overcome mass transfer limitations due to its unique properties. The process requires high-efficient catalysis a new class of bifunctional imidazole-based catalysts, and quaternary ammonium salts has been the chosen to perform a complete kinetic study about the carbonation of triglycerides in scCO2. Finally, an optimization study based on a screening experimental design of the operating conditions (T, P and catalyst ratio) is carried out, followed by a comparative study of the reaction performance through phase transition, that highlights a boosting effect caused by supercritical CO2 phase environment. At 120ºC, 125 bar of CO2 pressure and 7.5 mol% IOC (Iodine-based Imidazole Organo-Catalyst) catalyst ratio, the faster kinetic rate so far is for ESBO supercritical carbonation is obtained, kIOC= 2.28·10-1 h-1.